CHANGES IN PLASMA OF THE RAT DURING FASTING AND INFLUENCE OF GENETIC FACTORS UPON SUGAR AND CHOLESTEROL LEVELS

Abstract

Adult rats of the Osborne-Mendel (OM), Sprague-Dawley (SD), Holtzman (H) and Tumblebrook Farm hooded (TBH) strains were starved for 7 days, but allowed water ad libitum. Hb fell 1 g.% during the 1st day, and thereafter rose about 0.5 g.%/day. The plasma chloride concn. and albumin-globulin ratio rose slowly after the 5th day. In the OM, SD and H strains, the plasma levels of NPN, sugar and total protein fell during the first 2 days, rose on the 3d day to approx. the 24-hr. level, and fell again after the 5th day. In the TBH strain, the sugar level, initially less than in the others, did not rise on the 3d day or thereafter. The TBH was crossed with the OM and SD strains. In both crosses, the sugar levels of the F1 generation had a normal type of frequency distr. curve, whose mean was approx. the avg. of the parental means. The F2 distr. was bimodal, the modes approximating those of the grandparents, with almost no overlapping of the F1 distr. The cholesterol plasma levels in the SD and OM strains were double those in the TBH and H strains, and were unaffected by fasting. Following hypophysectomy, both "high" and "low" types rose to a new, equal level. Crossing the normal "high and "low" types led to an F1 of intermediate value and an F2 distr. typical of multiple factor inheritance.